jheronimus wrote:

486 is probably not the most practical choice for a second DOS machine (as opposed to 386)

Good luck, man! 486s are fun to mess with. You may have some success with combinations of L1, L2 and Turbo. My DX2-66 has speed points in the slow 486, fast 386, slow 386, and 286 ranges, through various manipulations of the caches and turbo. 😀

Specs

Getting a proper motherboard turned out to be the hardest part. I need something that has:

- a coin battery;
- no PCI slots (as much as I'd like to use PCI NIC);
- no 30pin SIMM slots — I'd like to have 4 "regular" 72pin ones;
- support for my AMD 5x86;
- a nice late VLB chipset like SIS471;

I might get an Aopen VI15G pretty soon that actually meets all the requirements. For now I have this cheap Chaintech 486SLP:

It doesn't use CR2032, but the barrel battery was replaced and no traces of leakage can be found:

You can also see the jumpers settings here. Looks like this motherboard might not support P75. However, it appears to have this DIY voltage regulator, so I might still get lucky:

Other core parts of this build are:

- NOS Cirrus Logic CL5428 VLB videocard with 1MB RAM (expandable to 2MB);
- NOS ASKA SST-2946 VLB multi I/O;
- Creative Sound Blaster AWE32 CT3990. Unfortunately, no OPL3. RAM is expanded to 2MB, but looks like I won't be able to use it in DOS;
- AMD 5x86. I'm actually getting a second one (also new old stock) with a fan later.

Finally, I'm going to use this case from my previous Pentium build:

For starters, I'm going to build a bare system with 486DX2 — it's more likely to be supported by this motherboard and I'll be able to test all other components.

I like this alot as Im going to build a very similar system!

First of all that motherboard should be plenty good enough for what you want to do as the sis chipset is highly regarded, the biggest hurdle will be enabling write back cache for optimal performance, have a look through this website, http://web.inter.nl.net/hcc/J.Steunebrink/amd … x86.htm#586upgr, wont be easy but trying to manipulate jumpers for the P24D settings for cache and try to determine the correct jumpers that set the multiplier to 2x.
Does the motherboard have voltage settings? They will need to be set for 3.3V but that looks like an older cpu socket...

dirkmirk wrote:

I like this alot as Im going to build a very similar system!

First of all that motherboard should be plenty good enough for what you want to do as the sis chipset is highly regarded, the biggest hurdle will be enabling write back cache for optimal performance, have a look through this website, http://web.inter.nl.net/hcc/J.Steunebrink/amd … x86.htm#586upgr, wont be easy but trying to manipulate jumpers for the P24D settings for cache and try to determine the correct jumpers that set the multiplier to 2x.
Does the motherboard have voltage settings? They will need to be set for 3.3V but that looks like an older cpu socket...

Thanks, dirkmirk!

The previous owner says that the last CPU used on this motherboard was AMD DX4-100. The jumper setting should be pretty similar if not identical. Not sure if I should use a 5x86 without a fan though (only have a passive heatsink at the moment).

editL wrong thread

White screen

Well, I can't boot it. Like, at all. Whenever I try to start the system, the screen just gradually gets very white and just stays that way. I don't get any POST sounds or anything. The CPU gets a bit warm though. Here is what I've tried:

1) different videocards:

I had a similar issue on my all-in-one Compaq Presario 433. With that machine a white screen usually meant a loose connection between the motherboard and the screen.

So at first I figured that it might be a videocard issue:

- tried putting my CL-5428 in a different VLB slot;
- tried changing it for an ISA videocard;
- tried different VESA jumper settings: 0-wait/1-wait state, >33MHz/<33MHz.

2) different CPUs

The previous owner confirmed that he used a DX4-100 on this mobo. To quote the dirkmirk's link about 5x86:

If you install the raw Am5x86 CPU, but you can't get the Am5x86 jumpers setting from the motherboard or system manufacturer, then start by setting all jumpers as for the Intel 486DX4-100 or, even better, the AMD Enhanced Am486DX4-100.

So I figured I should try the 5x86 "as is" first. That didn't work, and I decided to test the 486DX2@66 since it was listed in the motherboard's jumper table. Looked like I only needed to switch from 3v to 5v. Again, nothing.

3) different RAM

I tested several sticks of FPM RAM on my Socket 7 board. One pair of sticks actually gave it the same white screen issue (even though it worked in my Compaq flawlessly). The other pair checked out fine. Unfortunately, when I plugged the "good" sticks in Chaintech it didn't work.

A lot of progress & HDD issues

First, I found the manual for this motherboard. Turns out 4SLD is identical to my 4SLP. Here are jumper settings in TH99 and here is what Chaintech used to host for this motherboard.

Second, the white screen turned out to be a RAM issue. For some reason the sticks that worked in my Compaq and on my Socket 7 didn't work on this motherboard. After a lot of trial and error I found two identical 8 FPM MB sticks. They only worked properly when I plugged them into the first and third memory slot.

Third, I've configured the 5x86 using the jumper settings I've found. Now it's being detected as a DX4-100, which is OK for now.

Fourth, I'm stuck at the POST screen. The memory checks out OK, but no IDE devices get detected. Guess I'll have to revisit my MIO jumper settings.

This is looking very nice!

I've built a somewhat similar system over the last week. You can check it out here if you're interested.

You should take a look at the Terratec Maestro 32/96. It's a great Soundcard for DOS. Soundblaster Pro compatibility and high quality onboard Midi.

Did you check the IDE cable for PIN 1 correctly and try it as master with no other drives connected? Also make sure the controller is set as primary IDE. Your motherboard should be able to auto detect the HDD in the BIOS but you might want to try and set the HDD configuration manually if it doesn't.

If it still doesn't work after that I'd try the HDD in another machine and maybe try another HDD in this one. It might be that the drive is simply dead. These disks are quite old so getting a dead one isn't unheard of.

EDIT: If you have one you should try connecting the HDD to an IDE to USB adapter and check it on a modern computer. Run some diagnostics, do a surface scan and such.

Good Luck with your build! I look forward to seeing more.

jheronimus wrote:

Second, the white screen turned out to be a RAM issue. For some reason the sticks that worked in my Compaq and on my Socket 7 didn't work on this motherboard. After a lot of trial and error I found two identical 8 FPM MB sticks. They only worked properly when I plugged them into the first and third memory slot.

Then it's likely that if you want to add more memory, you'll need another identical pair that goes into the second and fourth slot. What is the difference between the sticks that work and those that don't work, parity?

Hellistor wrote:

This is looking very nice!

I've built a somewhat similar system over the last week. You can check it out here if you're interested.

Such a nice system! I've actually ordered the same motherboard, but the vendor had an accident in his warehouse and I'm not sure when I will get it or whether I will get it at all.

Hellistor wrote:

You should take a look at the Terratec Maestro 32/96. It's a great Soundcard for DOS. Soundblaster Pro compatibility and high quality onboard Midi.

I'm actually thinking about getting Dreamblaster X2 when it's out. All in all I prefer the daughterboard approach. But I'll keep an eye for this model — looks like it's not as expensive as Turtle Beach, Gravis or even AWE32.

Hellistor wrote:

Did you check the IDE cable for PIN 1 correctly and try it as master with no other drives connected? Also make sure the controller is set as primary IDE. Your motherboard should be able to auto detect the HDD in the BIOS but you might want to try and set the HDD configuration manually if it doesn't.

If it still doesn't work after that I'd try the HDD in another machine and maybe try another HDD in this one. It might be that the drive is simply dead. These disks are quite old so getting a dead one isn't unheard of.

This HDD was actually used in my Compaq, so I know for a fact that it works. Also, the system only starts when the sleeves are connected a certain way. I think I just have to check the jumpers/BIOS settings.

On a side note, this case turned out to be a huge pain in the ass for this motherboard. Basically all the IDE sleeves are too short for this kind of layout so I think I'll move the system to a baby AT tower case today.

yawetaG wrote:

Then it's likely that if you want to add more memory, you'll need another identical pair that goes into the second and fourth slot. What is the difference between the sticks that work and those that don't work, parity?

Frankly, I suck at identifying RAM 😀

1) All the EDO sticks don't work.
2) All the sticks that work, can be used individually or in pairs. Isn't that true for all FPM sticks?
3) placement matters. Right now my 2x8MB sticks are in slot 1 and 3. If I used them in slot 1 and 2, I would only get 12MB, not 16MB.

Not sure if I need 32MB though. I'm not going to use Windows 95/98 on it, and I thought anything more than 16MB may cause compatibility issues with games in "real" DOS.

jheronimus wrote:

On a side note, this case turned out to be a huge pain in the ass for this motherboard. Basically all the IDE sleeves are too short for this kind of layout so I think I'll move the system to a baby AT tower case today.

I take it that by sleeves you mean cables? If so, why don't you just use longer cables? I mean you stated that this is the case you want to use, so you should work around the caveats of building in it.

jheronimus wrote:

1) All the EDO sticks don't work.
2) All the sticks that work, can be used individually or in pairs. Isn't that true for all FPM sticks?
3) placement matters. Right now my 2x8MB sticks are in slot 1 and 3. If I used them in slot 1 and 2, I would only get 12MB, not 16MB.

RAM on these old boards is weird. I tried to get several sticks to run in my machine. Only RAM I could get running without trying every possible combination was the 32MB stick it came with or a 64MB stick. Which would have been overkill.

jheronimus wrote:

Not sure if I need 32MB though. I'm not going to use Windows 95/98 on it, and I thought anything more than 16MB may cause compatibility issues with games in "real" DOS.

I don't really see how more RAM would cause compatibility issues. at least not the bump from 16MB to 32MB. My machine hasn't had any problem so far. Thing is, if there are any problems you can still revert it anyway.
The AM5x86 133MHz is strong enough for games that can take advantage of the extra RAM so I'd say why not give it a try?

jheronimus wrote:

yawetaG wrote:

Then it's likely that if you want to add more memory, you'll need another identical pair that goes into the second and fourth slot. What is the difference between the sticks that work and those that don't work, parity?

Frankly, I suck at identifying RAM 😀

1) All the EDO sticks don't work.

Probably the main board is not compatible with EDO RAM.

2) All the sticks that work, can be used individually or in pairs. Isn't that true for all FPM sticks?
3) placement matters. Right now my 2x8MB sticks are in slot 1 and 3. If I used them in slot 1 and 2, I would only get 12MB, not 16MB.

On some motherboards, it will work fine with a single stick, but when you add more you need to add them in identical pairs placed in specific slots. Depending on the motherboard that is slots 1-3 and 2-4, or 1-2 and 3-4. Other motherboards don't have this limitation. It is a bit unusual to have this issue with a 486 board though...any chance this board is a server board?

Not sure if I need 32MB though. I'm not going to use Windows 95/98 on it, and I thought anything more than 16MB may cause compatibility issues with games in "real" DOS.

Can't say I ever had trouble running DOS games with 20 Mb RAM when I still had a 486... On the other hand, running DOS games on a system with DIMM slots instead of SIMM slots...

yawetaG wrote:

Probably the main board is not compatible with EDO RAM.

Well, to my knowledge, a 486 VLB board supporting EDO is more of an oddity than the norm.

Other motherboards don't have this limitation. It is a bit unusual to have this issue with a 486 board though...any chance this board is a server board?

I don't think so. This board was used in a regular school computer, AFAIK.

Can't say I ever had trouble running DOS games with 20 Mb RAM when I still had a 486... On the other hand, running DOS games on a system with DIMM slots instead of SIMM slots...

I'm not entirely sure about that bit. Just thought I've read something about RAM limitations while browsing topics on 486 systems here on Vogons.

MIO issues

Good news. Today I got my NOS AMD 5x86 and a cooler:

Bad news. I still can't get my MIO to work. I'm trying to at least boot from a floppy disk and this is as far as I'm getting:

What I've tried so far:

1) removed all cards. Right now only MIO and VGA card are in use.
2) removed all drives. Only a floppy drive is connected to the MIO at the moment. The drive is enabled in BIOS settings.
3) tried different drives/IDE cables/etc.
4) unassigned all the IRQs in BIOS. BTW, my card doesn't have PS/2, COM, LPT or IDE/FDD connectors. Should I have IRQs reserved in BIOS for those?
5) tried different jumper settings. Here are the jumper settings for my card:

The default settings are marked with * and I'm using those. I've only changed the LPT port to ECP mode and tried all four hard disk modes. In theory I should be using 25/33 mode, right?

Try enabling "Floppy drive seek at boot" in the BIOS, does the light flashes as it does the seeking operation or does it get stuck even before that? Not even a "FDD failure" message?

Also, do you have an ISA I/O card to test? I have experienced similar issues with VLB controllers in the past. Once I managed to get it working by swapping the positions of the VGA and the controller card, the I/O controller just refused to work if it was on the bottom slot. It worked when I installed the card in the middle VLB slot, and the VGA in the bottom one.

VLB controllers are nice since in many cases they have 2 IDE controllers, but performance wise I never noticed much of a difference with ISA in DOS (never used a caching controller though) and in my experience they are somewhat quirky to get working properly.

By the way, this build is looking really promising so I hope you solve your I/O controller issues. 😀

TheMobRules wrote:

Try enabling "Floppy drive seek at boot" in the BIOS, does the light flashes as it does the seeking operation or does it get stuck even before that? Not even a "FDD failure" message?

It is enabled. The light does flash as is tries seeking and it does a typical floppy startup sound, but I don't get any text message.

TheMobRules wrote:

Also, do you have an ISA I/O card to test? I have experienced similar issues with VLB controllers in the past. Once I managed to get it working by swapping the positions of the VGA and the controller card, the I/O controller just refused to work if it was on the bottom slot. It worked when I installed the card in the middle VLB slot, and the VGA in the bottom one.

Tried different VLB slots (and specifically putting MIO in the middle slot and the VGA in the bottom) — nothing 🙁

I remember reading that VLB cards are really sensitive to the CPU/FSB frequency — could that be an issue here? On the other hand the VGA card works without any issues,

jheronimus wrote:

Hellistor wrote:

Did you check the IDE cable for PIN 1 correctly and try it as master with no other drives connected? Also make sure the controller is set as primary IDE. Your motherboard should be able to auto detect the HDD in the BIOS but you might want to try and set the HDD configuration manually if it doesn't.

If it still doesn't work after that I'd try the HDD in another machine and maybe try another HDD in this one. It might be that the drive is simply dead. These disks are quite old so getting a dead one isn't unheard of.

This HDD was actually used in my Compaq, so I know for a fact that it works. Also, the system only starts when the sleeves are connected a certain way. I think I just have to check the jumpers/BIOS settings.

Do you have another HDD you can try? Compaq is one of those manufacturers that is somewhat notorious for using hardware that will only work in their own systems...

Regarding the VLB issue, the problem usually only occurs at bus speeds above 33 MHz. Have you tried the other hard disk modes on the controller?

yawetaG wrote:

Do you have another HDD you can try? Compaq is one of those manufacturers that is somewhat notorious for using hardware that will only work in their own systems...

ATM I'm trying to get the floppy drive to work, the HDDs are disconnected. However, the disk didn't come with a Compaq, it's just a Quantum Fireball 2.5 disk that I got with another non-branded Pentium machine.

Regarding the VLB issue, the problem usually only occurs at bus speeds above 33 MHz. Have you tried the other hard disk modes on the controller?

I've tried all the hard disk modes listed in the leaflet I posted above.

5x86 should be working at 4x33 by default. The CPU is identified as DX4-100 at the moment. I can't run the benchmarks, but even if it somehow works at 100 MHz now, it should be 3x33 anyways.